Video laryngoscope and video laryngoscope insertion section

ABSTRACT

A video laryngoscope and elongate laryngoscope insertion section for a video laryngoscope, comprising a viewing port through which an imaging device within the insertion section can obtain images of a larynx, the insertion section extending between a distal end for insertion into a subject and an opposite proximal end, and having an inferior surface and an opposed superior surface, wherein the insertion section comprises a proximal region where the insertion section extends through a subject&#39;s teeth in use, a distal region extending to the distal end and an intermediate region therebetween, wherein the inferior surface of the insertion section comprises or consists of a curved region which extends from the proximal region through the intermediate region to the distal region, wherein the curved region of the inferior surface is continuously longitudinally curved along the length of the longitudinally curved region and wherein the longitudinal curvature of the curved region of the inferior surface varies in the intermediate region. Markings on an elongate laryngoscope insertion can be used to monitor depth of insertion and to indicate a path by which an endotracheal tube should be inserted.

CROSS REFERENCE TO RELATED APPLICATION

This application is the Divisional of U.S. patent application Ser. No.14/894,464 filed 27 Nov. 2015, which is the U.S. national phase ofInternational Application No. PCT/GB2014/051673 filed 30 May 2014, whichdesignated the U.S. and claims priority to GB Patent Application No.1309714.2 filed 30 May 2013, the entire contents of each of which arehereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to the field of video laryngoscopes and insertionsections for video laryngoscopes.

BACKGROUND TO THE INVENTION

Laryngoscopes are medical devices in common use in oral and trachealmedical procedures, which may be used to obtain a view of the glottis orlarynx, or to manipulate the tongue, glottis or larynx in order tofacilitate insertion of endotracheal tubes or other instruments such asendoscopes, which may be separate pieces of equipment, or may beintegral to a laryngoscope.

Laryngoscopes comprise insertion sections, which are the elongate partof a laryngoscope which extends into a subject's oral cavity duringintubation. Insertion sections may be removably attachable to alaryngoscope body or integral parts of laryngoscopes or themselvesfunction as laryngoscopes. As well as an insertion section,laryngoscopes typically comprises a handle which is usually elongate andwhich may be arranged at an angle to the proximal end of the insertionsection or generally parallel to the proximal end of the insertionsection, or at any angle therebetween. The insertion section and handlemay be integrally formed.

Video laryngoscopes include an imaging device within the insertionsection. The imaging device is typically a camera but may be a lighttransmission device (e.g. one or more fibre optic cables) extending to acamera which is not in the insertion section, for example, within ahandle which remains outside of a subject's oral cavity in use. Theimaging device may be part of the insertion section but it is also knownfor the imaging device to be part of the body of the laryngoscope, forexample mounted to an insertion section retaining element which retainsa demountable insertion section. An example of such as a device is shownin EP 1638451 (McGrath). Such devices are advantageous in that thedemountable insertion section can be disposable and can protect theimaging device from contamination by bodily fluids, enabling the imagingdevice to be reused. The insertion section retaining element can also bea strengthening element, providing mechanical strength to the insertionsection. Video laryngoscopes may have an integral screen or transmitimages to a remote display through a wired or wireless interface.

Prior to the development of video laryngoscopes, intubation wastypically carried out using direct laryngoscopy. In direct laryngoscopy,the intubater seeks to obtain a direct line of sight view of a subject'slarynx. Some known insertion sections for laryngoscopes aresubstantially straight, such as Miller or Wisconsin blades. However, theblade of an insertion section is more commonly curved to better enterthrough a subject's oropharynx towards their larynx. For example, themost common curvature of an insertion section is what is commonly calledthe Macintosh curve. The curvature is relatively gentle and wheninserted into a subject's oral cavity, the gently curved blade is usedto lift and manipulate the tissue of the oral cavity, such as thetongue, out of the line of sight to allow an intubater a direct view ofthe subject's larynx.

However, video laryngoscopes enable a view of a subject's larynx to beobtained from an imaging device within the insertion section andtherefore within a subject's oral cavity in use, without having tosignificantly lift or manipulate the tongue. This enables an indirectview of the larynx to be obtained. Some video laryngoscope insertionsections have sufficiently shallow curvature to enable a direct view tobe obtained. In such cases, the ability to obtain a view of the larynxprior to intubation is of assistance but is not essential.

However, where there are anomalies within the oral cavity of thesubject, or where an effective view of the larynx cannot be achievedwith a direct view blade such as in instances where the subject's headand neck are not able to be moved to attain a direct line of sight ofthe larynx, it is often necessary to use an insertion section with agreater curvature to allow the blade to be inserted into the oralcavity. In this case, the intubater visualises the larynx indirectlyusing the video laryngoscope camera and screen. Insertion sections foruse where a user cannot normally obtain a direct line of sight view ofthe larynx are referred to herein as indirect view insertion sections.

Some aspects of the invention address the technical problem of providingan insertion section of suitable shape to facilitate intubation by videolaryngoscopy, particularly in relation to intubation of difficultairways. It is not uncommon for users, especially inexperienced users ofvideo laryngoscopes, to concentrate on obtaining the best possible viewfrom the camera of a video laryngoscope before starting to insert anendotracheal tube. In doing so, they typically insert the tip of theinsertion section too far into the subject's oral cavity, elevating theepiglottis directly. This can often result in a lack of sufficient roomto pass the endotracheal tube into the trachea as the tip of theinsertion section is too anterior in the subject's mouth in contrast towhen the tip of the insertion section is placed correctly fully into thevallecular to raise the epiglottis. This can cause a user to applyunnecessary force to try to make more room to pass the tube, or toposition the tube more anteriorly. Incorrect positioning of the blade inthe valecular can result in what is known as a “floppy epiglottis” (amisnomer used by users when epiglottis is lying in the line of sight ofthe vocal cords), usually caused by an insertion section not elevatingthe epiglottis appropriately to raise it out of the line of sight.

It is known to provide a substantially J-shaped insertion section, witha straight proximal region, a straight distal region and a defined bendor elbow therebetween. Likewise it is known to provide insertionsections with blades with a mixture of curved and straight sections withacute changes in angle or curvature between those sections (such asMcGrath Series 5, Glidescope and Belscope) Such insertion sections mayprovide a reasonable view of the larynx but are difficult to insert.Some aspects of the invention seek to improve the shape of an insertionsection to facilitate insertion into a subject, while enabling a goodview of the larynx to be obtained. It is preferable to minimisedistortion of tissue, avoid the use of excessive force and to avoidexcessive friction with the subject anatomy.

Some aspects address the shape of the inferior surface of the insertionsection as this surface contacts the patient's tongue during insertion.Some aspects address the shape of the insertion section as a whole, tofacilitate intubation.

Some aspects of the invention seek to address the problem of usersinserting an insertion section too far into a subject's mouth, orinsufficiently far. It has been proposed to provide a single marking onthe superior surface of a laryngoscope insertion section, indicative ofa dividing line between typical depth of insertion for an adult andtypical depth of insertion for a child. However, this is notsatisfactory as there is a significant variation in the correct depth ofinsertion of an insertion section between subjects within each group,and so a single indicator line is not of practical assistance.

Some embodiments of the invention address technical problems arisingfrom friction between an insertion section and a subject's tissues.Friction between an insertion section and tissues can cause trauma andaffect the safety of an intubation. For example, the subject's lips maystick to the insertion section and become dragged over the lowerincisors causing trauma and bleeding.

When intubating a subject using an indirect view laryngoscope, such as avideo laryngoscope, users who were trained with traditional direct viewMacintosh laryngoscopes may insert an endotracheal tube along the wrongpath. During traditional direct view laryngoscopy, an endotracheal tubeis run across the superior surface of the oral cavity. However, it ismore appropriate to run an endotracheal tube close to the insertionsection itself during indirect laryngoscopy. In insertion sections thathave a steeper curve, it is most appropriate that the endotracheal tuberuns close to the apex of the curve of the intermediate region of theinsertion section that traverses the oral cavity. Some aspects of theinvention address the problem of users inserting an endotracheal tubealong a path which was appropriate for traditional Macintoshlaryngoscopes, but which is not appropriate with a video laryngoscope,and more particularly an insertion section with a steep curve.

SUMMARY OF THE INVENTION

Within this specification and the appended claims, the inferior surfaceis the surface of an insertion section which faces the subject's tonguein use. The opposite surface is referred to as the superior surface.Words such as inferior, inferiorly, superior and superiorly are used incorresponding senses. A superior-inferior axis is a virtual axisextending parallel to the superior and inferior directions.

The words distal and distally refer to being towards the end of theinsertion section which extends towards a subject's trachea in use andthe words proximal and proximally refer to being towards the personcarrying out intubation in use.

According to a first aspect of the invention there is provided anelongate laryngoscope insertion section comprising a viewing portthrough which an imaging device within the insertion section can obtainimages of a larynx, the insertion section extending between a distal endfor insertion into a subject and an opposite proximal end, and having aninferior surface and an opposed superior surface, wherein the insertionsection comprises a proximal region where the insertion section extendsthrough a subject's teeth in use, a distal region extending to thedistal end and an intermediate region therebetween, wherein the inferiorsurface of the insertion section comprises or consists of a curvedregion which extends from the proximal region through the intermediateregion to the distal region, wherein the curved region of the inferiorsurface (the curved region) is continuously longitudinally curved alongthe length of the longitudinally curved region and wherein thelongitudinal curvature of the curved region of the inferior surfacevaries in the intermediate region.

The invention also extends in a second aspect to a video laryngoscopecomprising an elongate laryngoscope insertion section according to thefirst aspect of the invention and an imaging device within the insertionsection. The imaging device is configured to view images through theviewing port. The imaging device may be integral to the insertionsection. The imaging device may comprise a cavity (such as a channel)for receiving an insertion section retaining member and/or an imagingdevice. The imaging device is typically adjacent to or integral with theviewing port.

The viewing port is typically a window through which an imaging devicewithin the insertion section can view the larynx during use. The windowmay be integral to the imaging device, for example, the imaging devicemay be a camera comprising an imaging sensor and a lens and the windowmay be the lens of the camera. The window may not be flat, for example,it may comprise a prism to redirect light or other optical features.

The curved region typically extends along at least 80% or at least 90%of the length of the insertion section. Typically the curved regionextends along all of the length of the insertion section which wouldextend into the mouth of a subject during normal operation, exceptoptionally for the distal tip which may have another feature, such as abobble to facilitate sliding across tissues.

The curved region may extend to the proximal end of the inferior surfaceof the insertion section. The curved region may extend to the distal endof the inferior surface of the insertion section. The viewing port maybe in the intermediate region of the insertion section. However, in someembodiments, the distal region may extend from the viewing port to thedistal tip of the insertion section.

The curved region typically extends to the distal end of the inferiorsurface of the insertion section or to a bobble at the distal end of theinferior surface of the insertion section.

It may be that the curved region of the inferior surface has a minima oflongitudinal radius of curvature (maximum of longitudinal curvature) inthe intermediate region of the insertion section.

It may be that the longitudinal radius of curvature of the curved regionat the minima of longitudinal radius of curvature in the intermediateregion of the insertion section is less than at any point of the curvedregion in the proximal and distal regions (and so the longitudinalcurvature at the maximum of longitudinal curvature is greater than atany point of the curved region in the proximal and distal regions).

It may be that the longitudinal radius of curvature of the inferiorsurface varies continuously in the intermediate region.

Preferably, the inferior surface of the insertion section curves by morethan 90°, and typically more than 96°, more than 98° or more than 99°from the proximal end of the insertion section to the distal end of theinsertion section.

It may be that the longitudinal radius of curvature of the inferiorsurface in the intermediate region is not less than 75% (or not lessthan 85% or not less than 90%) of the minimum radius of curvature of theinferior surface in the proximal curved region.

By avoiding excessive longitudinal curvature in the intermediate region,the insertion section is easy to introduce into a subject. Thiscontrasts with insertion sections having a discrete corner, or elbow, inthe inferior surface.

The insertion section can therefore be rolled into a patient withoutpushing the anatomy around.

It may be that the longitudinal radius of curvature of the curved region(and therefore curvature) is constant in the proximal region.

It may be that the longitudinal radius of curvature of the curved region(and therefore curvature) is constant in the distal region.

We have found that it is especially advantageous to use an insertionsection having an inferior surface with a first constantly curved regionhaving a constant longitudinal radius of curvature (in the proximalregion of the insertion section) and a second constantly curved regionhaving a constant longitudinal radius of curvature (in the distal regionof the insertion section) with an intermediate region having a variablelongitudinal radius of curvature (which is typically less than thelongitudinal radius of curvature of the first or second constantlycurved regions) therebetween. The resulting shape is easier to insertthan an insertion section having an inferior surface which is straightalong much of the length, requiring a more defined bend or elbow.

Typically, the longitudinal radius of curvature of the curved region ofthe inferior surface has a minima in the intermediate region and thelongitudinal radius of curvature of the curved region of the inferiorsurface increases to at least 150% or 175%, or preferably at least 200%of the longitudinal radius of curvature of the curved region at the saidminima of longitudinal radius of curvature. (The minima of longitudinalradius of curvature is a maxima of curvature).

It may be that the longitudinal radius of curvature of the curved regionin the proximal region is less than the longitudinal radius of curvaturesurface of the curved region in the distal region.

The longitudinal radius of curvature is preferably less than four times,or less than three times, or less than double, or less than 150% of thestraight line distance from the proximal end to the distal end of theinferior surface of the insertion section, throughout the curvedsection.

The curved region may curve longitudinally in the proximal region of theinsertion section with a mean (or constant, where the longitudinalradius of curvature is constant) longitudinal radius of curvature of50%±5%, or preferably 50%±2.5% of the straight line distance from theproximal end of the insertion section to the distal end of the insertionsection.

The curved region may curve longitudinally in the distal region of theinsertion section with a mean (or constant, where the longitudinalradius of curvature is constant) longitudinal radius of curvature whichis equal to or greater than the straight line distance from the proximalend of the insertion section to the distal end of the insertion section.

It may be that the minimum longitudinal radius of curvature of thecurved region in the intermediate region is greater than 75% (andpreferably greater than 80%, greater than 85% or more preferably greaterthan 90%) of the minimum longitudinal radius of curvature of the curvedregion in the proximal region.

Where the curved region has a constant curvature in the proximal region,the minimum longitudinal radius of curvature of the curved region in theproximal region will be the longitudinal radius of curvature of thecurved region in the proximal region.

Accordingly, the maximum longitudinal curvature of the intermediateregion of the insertion section is less (and so the minimum oflongitudinal radius of curvature is greater) than in known laryngoscopeinsertion sections having a highly curved region or an elbow within theoropharynx in use.

The camera is situated in a similar location to insertion sections withacute changes in angle or curvature but without the awkward angle in theinsertion section. This is achieved by an insertion section with aunique curving profile with a varying radius of curvature in theintermediate region which runs seamlessly into the constant radius ofcurvature of the proximal region. This shape, in conjunction with theslim line profile means that the curve of the intermediate portion sitslower in the oral cavity in use, and as such less force is required onthe subject's tissues to place the tip of the blade in the vallecula andthe camera therefore in the optimum position so as to gain a sufficientanterior view from the camera whilst also allowing sufficient room forthe endotracheal tub to pass through the cords. This assists inovercoming known difficulty in placing the tube with a steeply curvedblade.

Typically, the breadth of the insertion section is less than the depthof the insertion section at at least one part of the proximal regionwhich is adjacent a subject's teeth in use.

By the breadth of the insertion section we refer to the lateral extent.By the thickness we refer to the displacement, parallel to a superiorinferior axis, from the most inferior point on the inferior side of theinsertion section to the most superior point on the superior side of theinsertion section, through a given cross section orthogonal to thelength of the insertion section.

The thickness of the insertion section may be constant in theintermediate region. The thickness of the insertion section may beconstant in the proximal region. The thickness of the insertion sectionmay be constant along the length of the insertion section at least fromthe proximal region to the viewing port. The thickness of the insertionsection may be constant along the length of the elongate member.

The laryngoscope insertion section preferably comprises an inferiorflange defining part of the inferior surface. The viewing port istypically located on a first lateral side of the insertion section andthe inferior flange is typically located on the opposite lateral side ofthe insertion section. The inferior flange typically extends distally ofthe viewing port. The inferior flange may define the distal end of theinsertion section. The inferior flange typically extends laterally ofthe elongate member (where present). It may be that the inferior flangeextends laterally of the elongate member (where present) at least as fardistally as the viewing port. It may be that the inferior flange extendslaterally of the elongate member (where present) to the distal end ofthe elongate member. It may be that the inferior flange may extendlaterally of the elongate member (wherein present) for less than 75%, orless than 60%, less than 50% or less than 40% of the distance along theinferior surface from the proximal end of the insertion section to theviewing port. The proximal end of the inferior flange may be tapered.This reduces the bulk of the inferior flange, facilitating tubeinsertion, while ensuring it extends laterally of the elongate memberwhere required.

A support flange may extend laterally from the insertion section toresist flexion of the insertion section and thereby provide mechanicalstrength. The support flange typically extends from the insertionsection in the opposite lateral direction to the inferior flange. Thesupport flange typically extends from the insertion section from thesame lateral side as the viewing port. Preferably the support flangeextends along less than half, and preferably less than 40% or less than30% of the length of the insertion section. Preferably, the supportflange extends past the point of maximum longitudinal curvature of thecurved region in the intermediate region of the insertion section.Preferably, the support flange extends past the viewing port (andtypically the imaging device).

Accordingly, the support flange is provided for only a limited portionof the length of the insertion section, keeping down the bulk of theinsertion section while providing mechanical strength.

It may be that the breadth of the insertion section is the same in theproximal region and the intermediate region.

It may be that the breadth of the insertion section in the intermediatesection is greater than the breadth of the insertion section in theproximal region (for example, by 1-5% or by 1-10%).

The insertion section may comprise an elongate member which extends fromthe proximal end of the insertion section at least as far in a distaldirection as the viewing port. A channel for receiving an insertionsection retaining member of a laryngoscope body having an insertionsection retaining member may extend from the proximal end of theelongate member. A flange may extend laterally from the inferior surfaceof the elongate member. The elongate member may have a constant breadth.The elongate member may be broader at the distal end of the elongatemember than the proximal end of the elongate member. The breadth of theelongate member may increase from the proximal end of the elongatemember to the distal end of the elongate member. The breadth of theelongate member may be 1-5% greater, or 1-10% greater adjacent theviewing port than at the proximal end of the elongate member.

This contrasts with known insertion section which are narrower at theviewing port than at the proximal end. Such devices function thereforehave a generally wedge shaped profile and can be difficult to manoeuvrein the mouth.

As mentioned above, the invention also extends to a video laryngoscopecomprising an elongate laryngoscope insertion section according to anyone preceding claim and an imaging device within the insertion section.

Preferably, the viewing port is located superiorly of a point which ismidway between the most inferior and most superior surfaces of theinsertion section. Preferably, the imaging device is located superiorlyof a point which is midway between the most inferior and most superiorsurfaces of the insertion section. Preferably, the imaging device islocated superiorly of a point which is 60% of the way from the mostinferior surface to the most superior surface of the insertion section.

The video laryngoscope may further comprise a display for displayingvideo images generated by the imaging device. The display may have aportrait orientation. That is to say, the images displayed on thedisplay may have greater height (extent parallel to theinferior-superior axis) than width (lateral extent). The imaging device(which is typically a camera) will typically also have a portraitorientation, that is to say it will measure images with a greaterangular spread in the inferior-superior axis than in a lateraldirection.

The portrait orientation of the imaging device and display facilitatesreliable intubation. This contrasts with known devices using a landscapeor lateral orientation which have been found to contribute to ‘tubeblind spot’ trauma risk with non-guided blades, due to the tube beingloose and largely out of the visual field, potentially causing softpalette and similar trauma during insertion, and only appearing on thelandscape display in the final moments before approaching the larynx. Itcan be preferable to provide an improved anterior view, while alsoproviding an improved view of the soft palette, where blind spot relatedtrauma can occur, to improve tube placement rather than to focuspredominantly on lateral view.

It may be that the insertion section is an indirect view insertionsection.

Typically, the maximum distance between the inferior surface of theinsertion section and a straight line extending from the proximal end tothe distal end of the inferior surface of the insertion section isgreater than 22%, greater than 23%, greater than 24% or greater than 25%of the length of a straight line extending from the proximal end to thedistal end of the inferior surface of the insertion section.

Typically, the inferior surface of the insertion section curves by morethan 90° and typically more than 95°, more than 97° or more than 99°between the proximal and distal ends.

According to a third aspect of the invention there is provided anelongate laryngoscope insertion section extending between a distal endfor insertion into a subject and a proximal end, and having an inferiorsurface and an opposed superior surface, wherein the superior surface isprovided with a plurality of markings which are substantially equallylongitudinally spaced.

Typically, the plurality of markings comprises at least three, or atleast four markings. The plurality of markings typically form a scale.The plurality of markings may be increments of length from the distalend of the insertion section. The plurality of markings are typicallyincrements of length from the distal end of the insertion section alongthe superior surface. Thus, they relate to the depth of insertion of theinsertion section relative to the upper maxillary incisor teeth. In thiscase, the plurality of marking are equally longitudinally spaced alongthe inferior surface of the insertion section. However, the plurality ofmarkings may be increments of straight line distance from the distal endof the insertion section. In this case, due to the curvature of theinsertion section, although the plurality of markings are equally spacedfrom the distal end of the insertion section, there a small variationbetween spacing measured along the inferior surface of the insertionsection.

The plurality of markings are located at the region of the insertionsection which is adjacent a subject's upper (maxillary) teeth duringintubation. The plurality of markings typically extend proximally anddistally of a subject's upper (maxillary) teeth during intubation, atleast for subjects at the middle of a range of sizes for which theinsertion section is sized.

The markings may comprise or be adjacent to numbers indicative of lengthfrom the distal end of the insertion section (for example length alongthe superior surface or straight line distance).

Accordingly, a user may view the longitudinally spaced markings andestablish the depth to which the insertion section has been introducedinto a subject. Typically they do so after inserting the insertionsection into a subject and before (and optionally during) insertion ofan endotracheal tube into the subjects' trachea. This is advantageous atis can guide a user to the optimum depth of insertion of the insertionsection into a subjects' oral cavity. The depth may also be recorded fortraining or monitoring purposes or can form part of the muscle memorytraining once optimal placement has been taught. The depth of insertionmay be recorded and later retrieved to facilitate subsequent intubationof the same subject.

Still further, the plurality of equally longitudinally spaced markingscan be referred to by a user to enable them to make an accurately judgedchange in the depth of insertion of the insertion section. They maydecide to move the insertion section further into or out of the subjectand use the plurality of markings to assess the distance by which theinsertion section has moved. Thus, it is not essential for numbersindicative of length from the distal end of the insertion section to beprovided.

The plurality of markings are also useful for communication duringtraining of a user. A trainer may give verbal instructions, referring tothe depth of insertion. The markings enable depth of insertion to bediscussed during a procedure, enabling two people to work together. Auser can look back and forwards repetitively between the markings on thesuperior surface of the insertion section and the display of the videolaryngoscope during positioning of the video laryngoscope or subsequentintubation. They, or an assist, teacher or supervisor, can mark down thedepth of insertion, or changes in depth of insertion, with reference tothe plurality of markings.

The insertion section may comprise a depth monitor to monitor the depthto which the insertion section is inserted into a subject.

The invention extends to an elongate laryngoscope insertion sectionextending between a distal end for insertion into a subject and aproximal end, and having an inferior surface and an opposed superiorsurface, the insertion section comprising a depth monitor for monitoringthe depth to which the insertion section is inserted into a subject.

The depth monitor may comprise a plurality of longitudinally spacedsensors for determining the extent to which the insertion section islocated in the subject's mouth. The longitudinally spaced sensors may belongitudinally spaced along the superior surface of the insertionsection. The longitudinally spaced sensors may be longitudinally spacedalong the inferior surface of the insertion section.

The sensors may be optical sensors. They may detect whether they are inthe patient's mouth from a decrease in the brightness of received light.

The invention extends to a video laryngoscope comprising the elongateinsertion section, a display and a processor which controls the display,wherein the processor is configured (e.g. programmed) to cause thedisplay to display information concerning the current or a previousdepth of insertion (typically relating to the same subject). Thelaryngoscope may comprise a memory and the processor may store ameasured depth of insertion in the memory. The processor may comprise anelectronic interface for receiving depth of insertion data from ortransmitting depth of insertion data to a remote patient data recorddatabase. The processor may be configured to cause the display todisplay an optimum or predetermined depth of insertion. The processormay be configured to cause the display to display an indicator as towhether the insertion section should be pushed further into, orretracted from, a subject's mouth.

The invention extends in a fourth aspect to a method of carrying outendotracheal intubation on a subject, the method comprising introducinga video laryngoscope comprising an elongate insertion section accordingto the third aspect of the invention into the subject, and thenadjusting the depth to which the insertion section is inserted into thesubject with reference to the plurality of markings on the superiorsurface.

The step of adjusting the depth to which the insertion section isinserted into the subject with reference to the plurality of markingsmay thereby guide a user as to the optimal placement of the insertionsection. The step of adjusting the depth to which the insertion sectionis inserted into the subject with reference to the plurality of markingscomprise guiding a user as to the distance by which they are adjustingthe longitudinal position of the insertion section within a subject'smouth.

The method may then comprised inserting an endotracheal tube into thesubject's trachea.

It may be that the depth of the insertion section is adjusted withreference to the plurality of markings after viewing the subject'strachea with the video laryngoscope and the method comprises thesubsequent step of introducing an endotracheal tube into the subject'strachea.

The invention extends in a fifth aspect to an elongate laryngoscopeinsertion section extending between a distal end for insertion into asubject and a proximal end, and having an inferior surface and anopposed superior surface, wherein the inferior surface and/or thesuperior surface comprise a microscopically rough region.

The elongate laryngoscope insertion section may comprise a continuousbody of clear plastic material which defines both a viewing port for animaging device, having a smooth surface, and the or each microscopicallyrough region.

The microscopically rough regions will have a reduced contact surfacearea with a subject's tissues compared to a completely smooth surface,reducing the risk of damage to a subject's tissues during intubation.Typically, the microscopically rough regions appear frosted. This is dueto light scattering by the microscopically rough regions. The smoothsurface of the viewing port need not be flat and indeed typicallycomprises one or more surface features, such as a prism.

Accordingly, the continuous body of clear plastic material has bothclear and frosted surface regions (where the surface is smooth and wherethe surface is microscopically rough respectively).

The invention extends in a sixth aspect to an elongate laryngoscopeinsertion section extending between a distal end for insertion into asubject and a proximal end, and having an inferior surface and anopposed superior surface, wherein the insertion section comprises anelongate member extending longitudinally along the insertion section anda lateral flange extending therefrom and having an inferior surfacewhich forms at least some (or all) of the inferior surface of thelaryngoscope insertion section, and an opposite superior surface,wherein the superior surface comprises a visual highlight.

The visual highlight indicates to a user the optimal path for anendotracheal tube to follow.

It may be that the insertion section comprises a viewing port throughwhich an imaging device within the insertion section can obtain imagesof a larynx and the visual highlight extends along the superior surfaceof the flange distally of the viewing port.

The visual highlight may comprise an arrow pointing towards the distalend of the insertion section.

The visual highlight may also form part of a physically defined contactzone along which the endotracheal tube should run if placed in theoptimal position so as to guide the intubater to position theendotracheal tube correctly. Such a contact zone may be added byinjection moulding or mould labelling which may be in a differenttexture to the rest of the insertion section, which may include a regionwhich does not have any microscopically rough regions.

The invention extends to a method comprising introducing a videolaryngoscope comprising an insertion section according to the sixthaspect of the invention into a subject's oral cavity, obtaining a viewof their larynx using the video laryngoscope, and then introducing anendotracheal tube adjacent to the visual highlight, or touching thevisual highlight with the endotracheal tube.

The invention extends in a seventh aspect to an elongate laryngoscopeinsertion section extending between a distal end for insertion into asubject and a proximal end, and having an inferior surface and anopposed superior surface, wherein the insertion section comprises anelongate member extending longitudinally along the insertion section,the elongate member having a lateral wall and an elongate guide lineextending longitudinally adjacent an optimal path for the insertion ofan endotracheal tube into the trachea of a subject into which theinsertion section has been introduced.

Accordingly, the guide line shows a user the path by which they shouldintroduce an endotracheal tube into a subject's trachea. Althoughespecially useful with an indirect view insertion section, particularlya more extremely curved insertion section, the feature may also beuseful with an insertion section capable of a direct view any in anycase helps to achieve the optimum placement of the endotracheal tubethrough the vocal cords under vision with the camera. The optimal pathfor an endotracheal tube would be the most direct route for the tube topass requiring the least curvature whilst hugging the apex of the curvebetween the proximal and the intermediate regions ie similar to a racingline. The invention extends to a method comprising introducing a videolaryngoscope comprising an insertion section according to the seventhaspect of the invention into a subject's oral cavity, obtaining a viewof their larynx using the video laryngoscope, and then introducing anendotracheal tube adjacent the guide line, with reference to the guideline.

The invention extends in an eighth aspect to a video laryngoscopecomprising a laryngoscope insertion section according to the first,third, fifth, sixth and/or seventh aspects of the invention. Optionalfeatures disclosed in relation to any one aspect of the invention areoptional features of each aspect of the invention.

The invention also extends to a laryngoscope insertion section having ashape substantially as shown in FIGS. 3A to 3G and FIG. 5.

The invention also extends to a laryngoscope insertion sectionsubstantially as described herein and illustrated with reference toFIGS. 3A to 3G and FIG. 5.

The invention also extends to a laryngoscope insertion section having ashape and dimensions substantially as shown in FIGS. 6A to 6C.

The invention also extends to a video laryngoscope comprising alaryngoscope insertion section as claimed.

DESCRIPTION OF THE DRAWINGS

An example embodiment of the present invention will now be illustratedwith reference to the following Figures in which:

FIG. 1 is a side view of a video laryngoscope comprising an insertionsection according to the present invention;

FIG. 2 is a corresponding side view showing a demountable insertionsection, mounted on an insertion section retaining member;

FIG. 3A is a bottom view of a laryngoscope insertion section;

FIG. 3B is a side view of the laryngoscope insertion section;

FIG. 3C is a plan view, from the inferior direction, of the insertionsection;

FIG. 3D is an opposite side view of the laryngoscope insertion section;

FIG. 3E is a perspective view from the distal end of the insertionsection;

FIGS. 3F and 3G are perspective views of the insertion section;

FIG. 4 illustrates the cross section of the insertion section throughA-A;

FIG. 5 illustrates the variation in radius of curvature of the inferiorsurface of an embodiment of the insertion section, with specifieddimensions;

FIGS. 6A, 6B and 6C are side, side and end views respectively of theinsertion section shown in FIG. 5;

FIG. 7A is a side view of a known laryngoscope insertion section havinga discrete bend in the inferior surface;

FIG. 7B is a side view of a known laryngoscope insertion having aninferior surface with a constant longitudinal curvature;

FIG. 7C is a side view of a standard laryngoscope with a Macintoshinsertion section;

FIG. 7D is a side view of a laryngoscope with insertion sectionaccording to the present invention;

FIGS. 7E, 7F and 7G illustrated the laryngoscope of FIG. 7D with theinsertion sections of FIGS. 7A, 7B and 7C respectively, overlaid asdashed lines;

FIG. 8 illustrates incorrect endotracheal tube placement;

FIG. 9 illustrates correct placement of an endotracheal tube using theinvention;

FIGS. 10A, 10B and 10C show the laryngoscope blade having variousmarkings;

FIG. 11 shows the inferior surface of the insertion section, withmarkings, uncurled; and

FIG. 12 is a lateral view of an insertion section.

DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT

With reference to FIGS. 1 to 12, a video laryngoscope 1 comprises ahandle 2 and an elongate insertion section 4 which extends from thehandle. The handle has a display 6 for showing video images obtained bya camera 8, using light obtained from an LED light source 10. The camerais located in the superior half of the insertion section. The insertionsection has a distal end 12 and an opposite proximal end 14. Theinsertion section has an inferior surface 16 which faces towards asubject's tongue in use and an opposite superior surface 18. An elongatemember 34 extends along the insertion section longitudinally from theproximal end and a flange 36 extends laterally from and distally of theelongate member and, along with the inferior surface of the elongatemember defines the inferior surface of the insertion section.

With reference to FIG. 2, the handle has an elongate insertion sectionretaining member 22 extending therefrom, and the insertion section hasan elongate channel 24 extending into the elongate member from theproximal end of the insertion section. The insertion section is formedfrom a transparent plastics material and includes a window 32,functioning as the viewing port, and having one or more prisms thereonto redirect light, to reduce light scattering and direct light from therequired direction into the camera. The insertion section retainingmember is formed from stainless steel and retains the camera 8 and lightsource 10, and the electrical wires (not shown) used to power the cameraand light source and to receive images for display on the monitor. Theelongate insertion section retaining member also functions as astrengthening element, resisting longitudinal bending and therebyproviding mechanical support to the insertion section. Accordingly, thecamera is in the insertion section but is not part of the insertionsection. It is connected to the handle through the insertion sectionretaining member and collects images through the window.

However, in some embodiments, the handle is formed integrally with theinsertion section. In some embodiments, the camera is part of theinsertion section.

With reference to FIGS. 3A through 3G, the insertion section has aproximal region 26, where the insertion section extends between asubject's teeth in use, a distal region 28, which extends to the distalend, and an intermediate region 30 therebetween. A first flange 36,shown for example in FIGS. 3E and 4, extends laterally of the elongatemember and distally of the viewing port and defines part of the inferiorsurface of the insertion section. A further flange 38 extends from alateral wall 20 of the elongate member on the opposite lateral side fromthe first flange, near the superior surface of the elongate member, andprovides additional mechanical support.

A bobble 40 is provided at the distal end of the insertion section, tohelp the tip of the insertion section glide across subject's tissues,and a clip 42, at the proximal end, retains the insertion sectiondemountably by a laryngoscope handle in use.

FIG. 5 illustrates the shape of the inferior surface of the insertionsection. It can be seen that the inferior surface of the insertionsection is continuously longitudinally curved at least from where itpasses between the subject's teeth during use, to the bobble at thedistal tip. This continuously curved section 44 functions as the curvedportion. However, the curvature is not constant and numerical values ofthe longitudinal radius of curvature along the length of the insertionsection are shown for a specific example embodiment. In the proximalregion, there is a constant radius of curvature (65.5 mm in thisexample). Progressing distally along the insertion section, thecurvature then increases in the intermediate region (and so the radiusof curvature, which decreases when the curvature increases, drops toabout 60 mm), and the curvature decreases again (and so the radius ofcurvature increases to about 135 mm), towards the distal end, such thatthe longitudinal curvature of the curved portion in the distal region isless than in the proximal region.

Accordingly, the longitudinal curvature is constant in the proximalregion. There is a further (relatively short) constant curvature regionnear the distal tip, and a variable longitudinal curvature sectionintermediate the two constantly curved sections.

It has been found that this curvature profile means that, when theinsertion section is positioned correctly, with the tip of the insertionsection in the vallecular, the curve of the insertion section sits lowerin the mouth in use than would be the case with a traditional Macintoshinsertion section, and involves less tissue manipulation as a result,but still follows the anatomy of the subject. When the blade iscorrectly used, with the optimum depth of insertion into the subject'smouth, less force is required by the user of the laryngoscope to elevatethe epiglottis than to gain a view of the vocal chords, than wouldotherwise be the case.

The flange 20 does not extend to the proximal end of the insertionsection but is spaced apart from the proximal end by about 20% of thelength of the insertion section portion. This makes the spatulateportion of the insertion section slim. This coupled with the sweepingsteep curve and the constant height which is less than the width at thenarrowest section of the insertion portion result in a blade whichaddresses the issue of optimising a sufficient anterior view from thecamera whilst also allowing sufficient room for the endotracheal tube topass through the cords.

FIG. 5 and FIGS. 6A through 6C illustrate an example of an insertionsection according to the present invention, with dimensions. The examplewhich is shown is for use in subjects requiring Size 4 endotrachealtubes. The shape will vary for subjects of different sizes. This is anindirect view insertion section and it can be seen from FIG. 6B that theinferior surface of the insertion section curves by 99.2° between theproximal and distal ends. With reference to FIG. 6A the maximum distancebetween the inferior surface of the insertion section is 29.3 mm, whichis 26.1% of the straight line distance between the proximal and distalends of the inferior surface of the insertion section (112.3 mm, shownin FIG. 6C). These figures are indicative of a relatively highly curvedinsertion section, for obtaining an indirect view, suitable for use withdifficult airways.

FIG. 7A is a view from a lateral direction of a known laryngoscopeinsertion section 80 (the dB5 disposable blade, available from AircraftMedical Limited, Edinburgh, UK) which has a proximal region 82 with aconstantly curved inferior surface 84, but a distal region 86 with astraight inferior surface 88 and a discrete bend 90 therebetween.

FIG. 7B is a view from a lateral direction of video laryngoscope with aknown direct view laryngoscope insertion section 100 (shown in WO2011/141751, Aircraft Medical) having an inferior surface 102 with aconstant curvature 104.

FIG. 7C is a view from a lateral direction of a widely-availabletraditional Macintosh laryngoscope, with a direct view insertion section110.

FIG. 7D is a view from a lateral direction of a laryngoscope insertionsection according to the present invention.

FIG. 7E shows the insertion section of the present invention with theinsertion section of FIG. 7A overlaid with a dashed line. It can be seenthat the laryngoscope of the present invention is more curved, but theinferior surface does not have a discrete bend making the insertionsection easier to insert.

FIG. 7F shows the insertion section of the present invention with theinsertion section of FIG. 7B overlaid with a dashed line. It can be seenthat the laryngoscope of the present invention is more longitudinallycurved, and has a variably longitudinal curvature, and provided a betterindirect view of the trachea, while retaining the benefit of having acontinuously longitudinally curved inferior surface, making it easy toinsert without subject trauma.

FIG. 7G shows the insertion section of the present invention with thetraditional Macintosh insertion section of FIG. 7C overlaid with adashed line. It can be seen that the laryngoscope of the presentinvention is more curved, providing a better angle to view the larynxindirectly during difficult airway intubations.

FIGS. 8 and 9 are cross-section through a subject undergoing trachealintubation with a laryngoscope having an insertion section according tothe invention. As the insertion section extends around the palette 52, agood view of the trachea 56 can be obtained from the camera. However, inFIG. 8, the insertion section has not been inserted correctly. Thedistal end of the insertion section restricts access of the endotrachealtube to the trachea. In FIG. 9, the insertion section has been insertedcorrectly. Users who are not familiar with video laryngoscopy mayinadvertently make the error shown in FIG. 8 as the best view of thelarynx is obtained when the insertion section has been inserted too farinto the subject.

The shape of the insertion section, particularly the constantly curvedinferior surface, with some greater, but not excessive, curvature in theintermediate region, has provided an insertion section which can bereadily rolled into a patient, without the user having to push thepatient's anatomy around. Without the curvature in the proximal regionit is necessary to provide an excessively curved bend, which typicallymanifests itself in the camera region.

With reference to FIGS. 10A and 10B a longitudinal scale is provided onthe superior surface of the insertion section, formed by a plurality ofmarkings 70, which are equally longitudinally spaced. In this example,the markings are numbers, spaced apart by 1 cm, and each is a measure ofthe distance from the marking to the distal end of the insertionsection, along the superior surface of the insertion section.

The markings enable a user to assess the depth of insertion of theinsertion section, by reference to the position of the markings relativeto the upper (maxillary) incisor teeth of the subject. This enables auser to determine the optimum depth of insertion, and the optimumtechnique for using a video laryngoscope with the insertion section.

The absolute value of depth of insertion may be recorded for aparticular subject. The depth of insertion which is employed in aparticular procedure may be stored, to provide a record of theprocedure. The optimum depth of insertion may be looked up, for example,from a table of suitable depth of insertions for given sizes of thesubject, or from measurements of the subject.

The markings can be used during intubation to avoid excessive insertionof the insertion section as shown in FIG. 8. The markings can also beused to make relative adjustments of depth of insertion, for example anoptimum view can be obtained, and the user might then retract theinsertion section by a predetermined distance, for example 1 cm, usingthe position of the markings relative to the subject's maxillary teeth,to judge the distance of movement.

With reference to FIGS. 10A, 10C and 11, a visual highlight 60 isprovided on the superior surface of the flange 36. The visual highlightserves to indicate to a user that they should insert the endotrachealtube along a path which is very close to, or touching the superiorsurface of the flange. The visual highlight may comprise one or more ofan arrow pointing in a distal direction, a picture of an endotrachealtube and text. The visual highlight may indicate a contact zone which anendotracheal tube should contact during insertion. The visual highlightmay be moulded. The visual highlight may be printed. The visualhighlight may be etched. The visual highlight may be an embedded image,for example during moulding (e.g. using a twin shot mould).

With reference to FIG. 12, the lateral wall of the insertion section hasan elongate guide line 65 extending longitudinally adjacent an optimalpath for the insertion of an endotracheal tube into the trachea of asubject into which the insertion section has been introduced. The guideline, which might for example be a ridge or image, assists a user inintroducing a tube along the optimum line.

The optimum line for introduction of an endotracheal tube generally hugsthe longitudinal curve of the superior surface of the flange adjacentthe viewing port. The optimum line for introduction may be the mostdirect route for an endotracheal tube, typically taking into account thebuilt in curvature of an endotracheal tube. The optimum line may requireleast flexion of the endotracheal tube.

In some embodiments, the insertion section includes one or moremicroscopically rough surface regions located on the inferior andsuperior surfaces of the insertion section. Microscopically roughsurface sections can be obtained by corresponding texturing of a mouldused to form the insertion section, or by grinding, for example.

The microscopically rough surface sections present a lower contact areato skin than would be the case if the surfaces were completely smooth,reducing friction. This has the effect of a reducing the risk of damageto the lips, which might otherwise be dragged onto and cut by asubject's teeth during use.

The microscopically rough areas scatter light and so give the insertionsection a frosted appearance. However, the microscopically rough surfaceregions do not extend across the viewing port, where they would blockthe camera. In these embodiments, an insertion section withmicroscopically rough surface regions on the inferior and superiorsurface, but not on the viewing port, can be made predominantly, and insome embodiments entirely, from a single moulded transparent plasticspiece.

Further variations and modifications fall within the scope of theinvention herein disclosed.

The invention claimed is:
 1. An elongate laryngoscope insertion sectioncomprising a viewing port through which an imaging device within theinsertion section can obtain images of a larynx, the insertion sectionextending between a distal end for insertion into a subject and anopposite proximal end, and having an inferior surface and an opposedsuperior surface, wherein the insertion section comprises a proximalregion where the insertion section extends through a subject's teeth inuse, a distal region extending to the distal end and an intermediateregion therebetween, wherein the inferior surface of the insertionsection comprises a curved region which extends from the proximal regionthrough the intermediate region to the distal region, wherein the curvedregion of the inferior surface is continuously longitudinally curvedalong the length of the longitudinally curved region and wherein thelongitudinal curvature of the curved region of the inferior surface:varies in the intermediate region; and is constant in at least one ofthe distal region or the proximal region.
 2. An elongate laryngoscopeinsertion section according to claim 1, wherein the curved region of theinferior surface has a minima of longitudinal radius of curvature in theintermediate region of the insertion section.
 3. An elongatelaryngoscope insertion section according to claim 2, wherein thelongitudinal radius of curvature at the minima of longitudinal radius ofcurvature of the curved region in the intermediate region of theinsertion section is less than at any point of the curved region in theproximal and distal regions.
 4. An elongate laryngoscope insertionsection according to claim 2, wherein the longitudinal radius ofcurvature of the curved region of the inferior surface variescontinuously in the intermediate region.
 5. An elongate laryngoscopeinsertion section according to claim 2, wherein the longitudinal radiusof curvature of the curved region of the inferior surface in theintermediate region is not less than 75% of the minimum radius ofcurvature of the inferior surface in the proximal curved region.
 6. Anelongate laryngoscope insertion section according to claim 2 wherein thelongitudinal radius of curvature of the curved region of the inferiorsurface is constant in the proximal region.
 7. An elongate laryngoscopeinsertion section according to claim 2, wherein the longitudinal radiusof curvature of the curved region of the inferior surface is constant inthe distal region.
 8. An elongate laryngoscope insertion sectionaccording to claim 7, wherein the longitudinal radius of curvature ofthe curved region in the proximal region is less than the longitudinalradius of curvature surface of the curved region in the distal region.9. An elongate laryngoscope insertion section according to claim 1,wherein the minimum longitudinal radius of curvature of the curvedregion in the intermediate region is greater than 80% of the minimumlongitudinal radius of curvature of the curved region in the proximalregion.
 10. An elongate laryngoscope insertion section according toclaim 1, wherein the insertion section is an indirect view insertionsection.
 11. An elongate laryngoscope insertion section according toclaim 1, wherein the superior surface is provided with a plurality ofmarkings which are substantially equally longitudinally spaced.
 12. Anelongate laryngoscope insertion section extending between a distal endfor insertion into a subject and a proximal end, and having an inferiorsurface and an opposed superior surface, wherein the superior surface isprovided with a plurality of markings which are variably spaced based ona curvature of the insertion section, and wherein the interior surfacehas a first portion with a constant radius of curvature and a secondportion with a variable radius of curvature.
 13. An elongatelaryngoscope insertion section according to claim 12, wherein theplurality of markings are increments of length from the distal end ofthe insertion section along the superior surface.
 14. An elongatelaryngoscope insertion section according to claim 12, wherein theplurality of markings are in increments of straight line distance fromthe distal end of the insertion section.
 15. An elongate laryngoscopeinsertion section according to claim 12, wherein the insertion sectioncomprises a depth monitor to monitor the depth to which the insertionsection is inserted into a subject.
 16. An elongate laryngoscopeinsertion section according to claim 15, wherein the depth monitorcomprises a plurality of longitudinally spaced sensors for determiningthe extent to which the insertion section is located in the subject'smouth.
 17. An elongate laryngoscope insertion section according to claim12, wherein an individual marking of the plurality of markings comprisesa numerical indicator representative of a distance from the individualmarker to the distal end.
 18. An elongate laryngoscope insertion sectionaccording to claim 12, wherein the plurality of markings terminateproximally of a viewing port forming an end face of an elongate channelof the insertion section.
 19. A laryngoscope comprising: a displayscreen; an imaging device; and an elongate laryngoscope insertionsection comprising: a viewing port through which the imaging device canobtain images of a larynx, the insertion section extending between adistal end for insertion into a subject and an opposite proximal end; aproximal region where the insertion section extends through a subject'steeth in use; a distal region extending to the distal end; anintermediate region between the distal region and the proximal region,an inferior surface having a curved region that extends from theproximal region through the intermediate region to the distal region,wherein the inferior surface of the insertion section comprises a curvedregion which extends from the proximal region through the intermediateregion to the distal region, wherein the curved region of the inferiorsurface is continuously longitudinally curved along the length of thelongitudinally curved region and wherein the longitudinal curvature ofthe curved region of the inferior surface: varies in the intermediateregion; and is constant in at least one of the distal region or theproximal region.